Adjustable posterior spinal column positioner

Abstract

Height-adjustable devices suitable for insertion between posterior spinal processes that allow the surgeon to post-operatively adjust the height of the implant.

1. A spinal implant for insertion into a space between a first and second posterior process, the spinal implant comprising:
 a) a first body having:
 i. an upper bearing surface for bearing against a first process, 
 ii. an outer side surface having upper and lower extensions extending therefrom in an axial direction, 
 iii. an inner surface 
 iv. a gear attached to the inner surface having a first set of teeth, each tooth having an apex, 
 
 b) a second body having:
 i. a lower bearing surface for bearing against a second process, 
 ii. an outer side surface having upper and lower extensions extending therefrom in the axial direction, 
 iii. an inner surface having a second set of teeth, each tooth having an apex, 
 
 
     wherein the first set of teeth is radial and the second set of teeth is linear, 
     and wherein the apex of each tooth in the first set of teeth is in a radial arrangement relative to each other, 
     and wherein the apex of each tooth in the second set of teeth is in a linear arrangement relative to each other, 
     wherein the first set and second set of teeth cooperate such that, upon rotation of the gear, the upper bearing surface moves relative to the lower bearing surface, thereby changing a height of the spinal implant. 
   
   
     2. The implant of  claim 1  further comprising a locking mechanism positioned to fix the gear. 
   
   
     3. The implant of  claim 1  further comprising an actuation rod attached to the center of the gear. 
   
   
     4. The implant of  claim 1  wherein the gear is magnetic. 
   
   
     5. The implant of  claim 1  wherein at least one bearing surface extends substantially to an inner side of one of the extensions.